Hello.
This project I have is to let arduino play human voice with the PWM sample we found on the playground, with the difference that this one is getting the data from a serial connection.
The problem is that if the arduino gets the data from a USB connection, the audio quality is fine, but If it gets the data wirelessly from an xBee, then the sound is really really poor (almost pure noise).
Please help me, I have tried everything, and a I'm a newbie on this.
int a = 0;
int ledPin = 13;
int speakerPin = 11;
char inData[3];
char numero[3]; // Allocate some space for the string
char inChar; // Where to store the character read
byte index = 0; // Index into array; where to store the character
long arraySize = 999999;
byte num;
/*
* speaker_pcm
*
* Plays 8-bit PCM audio on pin 11 using pulse-width modulation (PWM).
* For Arduino with Atmega168 at 16 MHz.
*
* Uses two timers. The first changes the sample value 8000 times a second.
* The second holds pin 11 high for 0-255 ticks out of a 256-tick cycle,
* depending on sample value. The second timer repeats 62500 times per second
* (16000000 / 256), much faster than the playback rate (8000 Hz), so
* it almost sounds halfway decent, just really quiet on a PC speaker.
*
* Takes over Timer 1 (16-bit) for the 8000 Hz timer. This breaks PWM
* (analogWrite()) for Arduino pins 9 and 10. Takes Timer 2 (8-bit)
* for the pulse width modulation, breaking PWM for pins 11 & 3.
*
* References:
* http://www.uchobby.com/index.php/2007/11/11/arduino-sound-part-1/
* http://www.atmel.com/dyn/resources/prod_documents/doc2542.pdf
* http://www.evilmadscientist.com/article.php/avrdac
* http://gonium.net/md/2006/12/27/i-will-think-before-i-code/
* http://fly.cc.fer.hr/GDM/articles/sndmus/speaker2.html
* http://www.gamedev.net/reference/articles/article442.asp
*
* Michael Smith <michael@hurts.ca>
*/
#include <stdint.h>
#include <avr/interrupt.h>
#include <avr/io.h>
#include <avr/pgmspace.h>
#define SAMPLE_RATE 8000 //8KHz sample rate
/*
* The audio data needs to be unsigned, 8-bit, 8000 Hz, and small enough
* to fit in flash. 10000-13000 samples is about the limit.
*
* sounddata.h should look like this:
* const int sounddata_length=10000;
* const unsigned char sounddata_data[] PROGMEM = { ..... };
*
* You can use wav2c from GBA CSS:
* http://thieumsweb.free.fr/english/gbacss.html
* Then add "PROGMEM" in the right place. I hacked it up to dump the samples
* as unsigned rather than signed, but it shouldn't matter.
*
* http://musicthing.blogspot.com/2005/05/tiny-music-makers-pt-4-mac-startup.html
* mplayer -ao pcm macstartup.mp3
* sox audiodump.wav -v 1.32 -c 1 -r 8000 -u -1 macstartup-8000.wav
* sox macstartup-8000.wav macstartup-cut.wav trim 0 10000s
* wav2c macstartup-cut.wav sounddata.h sounddata
*/
//#include "sounddata.h"
#define SAMPLEINDEX_MASK 0x0FFF
//Used to implement phase increment resampling
uint16_t sampleStep; //The step size for each sample. All 16 bits are used.
//The lower 12 are fractional steps. A step size of 0x01000 is equal to one step
//per sample. Also, this means that playback can be done at a maximum of 16X the
//orignal rate.
volatile unsigned long sampleIndex; //Keeps the current sample index.
//Used by the ISR and initalizaiton methods
uint16_t samplePoint;
unsigned int sampleValue;
//Prototype for DAC output function
//The idea is to abstract the type of DAC used. It is assumed that the DAC would never have more then
//16 bits of resolution so an unsigned int is used. If you intened to have 8-Bits of resolution then you
//need to upshift the input (value<<8). This does add some time/hassel but it support the concept of
//differnet resolutions independent of the applicaiton code.
//The second parameter is the DAC channel. For the inital test code one is used for the PWM DAC and
//and the other is for the R2R DAC. In a future version I want to have Left and Right channels
//
#define DAC_PWM 1
#define DAC_R2R 2
void SetDAC(unsigned int outputValue, unsigned int channel);
//Lower level funcitons to actualy set the specific DAC type. Used only by the SetDAC funciton.
void SetDAC_PWM(unsigned int outputValue);
void SetDAC_R2R(unsigned int outputValue);
ISR(TIMER1_COMPA_vect) {
}
void startPlayback() {
pinMode(speakerPin, OUTPUT);
sampleStep=0x2000; //Set to orignal sample rate.
// Set up Timer 2 to do pulse width modulation on the speaker
// pin.
// Use internal clock (datasheet p.160)
ASSR &= ~(_BV(EXCLK) | _BV(AS2));
// Set fast PWM mode (p.157)
TCCR2A |= _BV(WGM21) | _BV(WGM20);
TCCR2B &= ~_BV(WGM22);
// Do non-inverting PWM on pin OC2A (p.155)
// On the Arduino this is pin 11.
TCCR2A = (TCCR2A | _BV(COM2A1)) & ~_BV(COM2A0);
TCCR2A &= ~(_BV(COM2B1) | _BV(COM2B0));
// No prescaler (p.158)
TCCR2B = (TCCR2B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10);
// Set initial pulse width to the first sample.
//sampleValue=pgm_read_byte(&sounddata_data[0])<<8;
//sampleValue = num;
// SetPWMDAC(sampleValue);
// SetR2RDAC(sampleValue);
// Set up Timer 1 to send a sample every interrupt.
// cli();
// Set CTC mode (Clear Timer on Compare Match) (p.133)
// Have to set OCR1A *after*, otherwise it gets reset to 0!
TCCR1B = (TCCR1B & ~_BV(WGM13)) | _BV(WGM12);
TCCR1A = TCCR1A & ~(_BV(WGM11) | _BV(WGM10));
// No prescaler (p.134)
TCCR1B = (TCCR1B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10);
// Set the compare register (OCR1A).
// OCR1A is a 16-bit register, so we have to do this with
// interrupts disabled to be safe.
OCR1A = F_CPU / SAMPLE_RATE; // 16e6 / 8000 = 2000
// Enable interrupt when TCNT1 == OCR1A (p.136)
TIMSK1 |= _BV(OCIE1A);
// lastSample = pgm_read_byte(&sounddata_data[sounddata_length-1]);
//sampleIndex = 0;
// sei();
}
void SetDAC(unsigned int outputValue, unsigned int channel) {
switch(channel) {
case DAC_PWM :
SetDAC_PWM(outputValue);
break;
case DAC_R2R :
SetDAC_R2R(outputValue);
break;
}
}
//Set the PWM D/A converter output
void SetDAC_PWM(unsigned int outputValue){
//This implementation uses PWM in 8 bit mode.
//Load the upper 8 bits into the PWM control register
OCR2A = (outputValue>>8)&0xFF;
}
//Set the R2R D/A converter output.
void SetDAC_R2R(unsigned int outputValue){
//We are using port D bits 2-7 for a 6-bit D/A.
//Bits 0 and 1 are serial which we dont want to disturb
PORTD=(PIND&0x03)|((outputValue>>8)&0xFC);
}
#define MAX_STEP 0x05000
#define MIN_STEP 0x00400
void setup() {
//Set the LED pin mode to output.
pinMode(ledPin, OUTPUT);
//Iniciar el serial a 115200 bps
Serial.begin(142500);
//2 bits de paro / 2 stop bits
// UCSR0C = UCSR0C | B00001000;
// UCSR0C |= (1 << USBS0); // right after calling Serial.begin ();
pinMode(speakerPin, OUTPUT);
//Setup the hardware for the D/A converter
//We are using port D bits 2-7 for a 6-bit D/A.
//Bits 0 and 1 are serial which we dont want to disturb
// DDRD|=B11111110; //Set upper 6 as ouput, lower are TX and RX
//Set an inital phase step size.
sampleStep=MIN_STEP;
//Setup the timers for the ISR and PCM generation
startPlayback();
//Parpadear LED para indicar que funciona correctamente
for (int i = 0; i<3; i++){
digitalWrite(ledPin,HIGH);
delay(250);
digitalWrite(ledPin,LOW);
delay(250);
}
}
void loop() {
//To demonstrate the phase steping feature set the phase step as a function
//of the A/D input on input 0. Hook up a pot to vary the phase step and resample the
//sound at diffenret frequencies.
//for(int i = 0; i<255;i++)
//sampleStep=MIN_STEP+(analogRead(0)<<3);
//sampleStep=MIN_STEP+i;
while(Serial.available() > 0) // Don't read unless you know there is data
{
digitalWrite(ledPin,HIGH);
if(index < arraySize) // One less than the size of the array
{
inChar = Serial.read(); // Read a character
//Que reciba caracteres hasta que llegue una coma
if (inChar!=','){
inData[index] = inChar; // Store it
index++; // Increment where to write next
inData[index] = '\0'; // Null terminate the string
}
//Si el caracter es coma, que lo mande a numero
if(inChar==','){
for(int i = 0; i<3;i++){
numero[i]='\0';//Borrar cada caracter de numero para poder escribir en el de nuevo
if(inData[i]!='\0')
numero[i] = inData[i];
}
//Ahora en entero
char * thisChar = numero;
a = atoi(thisChar);
num = a;
index = 0;
}
}
//delay(10);
OCR2A = num;//QUe lo saque por el pwm
//SetDAC(a, DAC_PWM);
digitalWrite(ledPin,LOW);
}
}
:-[